It finally relented, agreeing to the recall and subsequently demonstrating that the simple addition of a trailer hitch to these vehicles could reduce the fire risk.

However, Chrysler did not even select a supplier to make these hitches until the end of 2013, and the sluggish rate of output of the hitches meant it could take several years for the recalled vehicles to all be fixed.

NHTSA, itself under fire for failing to push General Motors to recall Chevy Cobalts and other vehicles involved in the ignition switch scandal, recently began putting pressure on Chrysler to answer for its delay in repairing these Jeeps.

Yesterday, Chrysler responded to the agency’s queries, saying it is speeding up production of the hitches, but that it can’t begin repairs until it receives the first batch of parts in August.

Even with the increased production, Chrysler still says it won’t have enough parts to repair all affected Jeeps until March 2015, nearly two years on from the recall announcement.

Some have questioned whether the addition of the hitch will indeed suffice to reduce the risk of fire. Even Chrysler’s own report on the fix said the hitch would only “incrementally improve the performance in certain types of low-speed impacts.”

NHTSA tested the hitch fix and determined that “the risk of fuel tank ruptures and fires in lower to medium-speed rear-end crashes will be successfully reduced by the remedy.” However, the agency did not test what would happen in collisions at speeds greater than 43 mph. Critics of the hitch plan say that Jeep passengers have survived high-speed crashes but died in resulting fires.

The initial recall involved some 2.7 million Jeeps, but Chrysler says that, given the age of some of these vehicles (the Grand Cherokee recall included model years as far back as 1993), only about 1.6 million remain on the road.